I am testing the RF amplifier on a PN532 breakout board for a better reading distance as discussed in AN1425. Finally I want to identify the tiny 2* 12 glass tag with PN532 chip.
I use this PN532 board(https://www.adafruit.com/product/364 ). Its matching circuit matches with its antenna very well.
Without any amplifier, the reading distance is about 10cm for a 85mm*54mm rfid card and about 1.5cm for this tiny glass tag.
After adding the amplifier into this breakout board, the big card distance decreases to less than 5CM, the glass tag can not be identified. The values of amplifier components are from Table 6 in the AN1425 document. I did not change other components in the breakout board.
So I want to know,
(1)After adding this amplifier circuit, I need to do the antenna matching task again?
(2)"The PN5xx has two transceiver pin: TX1 and TX2. By using the amplifier solution, the contactless reader transmission mode should be switched to asynchronous mode. This is done by setting the register 0x14(TXControlReg) to 0x83".
This is from Page 7 of the AN1425 document.
For the PN532 chip, how can I switch to asynchronous mode? I can not find the TXControlReg register in its datasheet and user manual.
Appreciate for any other good suggestion.